The mechanism for the conversion of delta 1-3,4-cis THC to delta 6-3, 4-trans-THC with BBr3 was investigated. It was determined that the main epimerization occurs at C-4 and is accompained by some racemization or competitive epimerization at C-3 (Tetrahedron 34, 1885 (1978). The synthesis of (-)-delta9-THC and its biologically potent metabolite -3'-hydroxy-delta9-THC was achieved using a new synthon via p-menth-2-ene-1,8-diol (Tetrahedron Letters, 681 (1978). A completely new and versatile approach to the synthesis of delta1-THC metabolites was developed utilizing a terpene containing the 1,3-dithiane moietry (J. Amer. Chem. Soc., 100, 2929 (1978). We have recently reported a practical one step synthesis of delta9-THC (J. Amer. Chem. Soc., 96, 5860 (1974). This process has been successfully scaled up to provide delta9-THC in gram quantities.